Australia as a whole is largely forced to hug the eastern coast of the country. 70% of the country is arid desert, so the population is scattered linearly, which is actually quite perfect for rail based transport.
The population distribution of the U.S. is far more spread out, so to build enough rail or bus lines to make it so that you don't have to walk more than a quarter mile to a station is impractical for all but the densest cities or denses parts of urban corridors.
The population distribution of the U.S. is far more spread out, so to build enough rail or bus lines to make it so that you don't have to walk more than a quarter mile to a station is impractical for all but the densest cities or denses parts of urban corridors.